A thermoelectric element includes a thermistor that uses a property of a semiconductor in which electric resistance is greatly changed by a very small change in temperature and uses a change in temperature caused by electric resistance. A thermoelectric element uses the Seebeck effect, which is a phenomenon in which electromotive force is generated by a difference in temperature between two different metallic joint portions and in which electromotive force (force which generates an electric potential difference between two points and allows an electric current to flow) is generated by a difference in temperature. A Peltier element uses a Peltier effect which is a phenomenon in which heat is absorbed or generated by an electric current.
The thermistor is a semiconductor element in which the electric resistance greatly changes by the change in temperature. The thermistor element includes a negative temperature coefficient (NTC) thermistor in which electric resistance is greatly decreased by an increase in temperature and a PTC thermistor in which resistance is increased by an increase in temperature. The thermistor is manufactured by mixing a plurality of components of oxides that include molybdenum, nickel, cobalt, iron, and the like and by sintering the mixture, and is used to stabilize a circuit and to detect heat, electric power, light, and the like.
In the Seebeck effect, electromotive force is generated when both ends of two different metals are joined together and temperatures at both ends become different from each other, and the Seebeck effect is applied to measure a temperature using a thermocouple.
The Peltier effect, which is used for electronic cooling, refers to a phenomenon in which when ends of two different of metals are joined together and an electric current flows through the ends, one end absorbs heat and another other end generates heat in accordance with a direction of the electric current. When semiconductors such has bismuth, tellurium, and the like having different electrical conductivity are used instead of the two different of metals, the Peltier element may efficiently absorb and generate heat.
The heat absorbing and generating operation of the Peltier element may vary in accordance with a direction of an electric current, and the amount of absorbed heat and the amount of generated heat may be adjusted by the amount of electric currents. Therefore, the Peltier element is mainly used to manufacture a refrigerator with a small capacity or a precise thermostat that is used at about room temperature.
A heat radiating part of a thermoelectric element needs to be efficiently cooled to improve cooling performance according to the heat absorbing and generating operation and thus to improve cooling performance of the opposite heat absorbing part.
However, in the existing system for cooling the heat radiating part of the thermoelectric element is directly disposed on a ceramic plate of a module, and thus is not efficient because the system adopts only one of a water cooling function and an air cooling function.
Therefore, it is required to provide a thermoelectric element system which increases an area of the heat radiating part and which improves cooling efficiency by using a water cooling function and an air cooling function at the same time.
In order to satisfy the aforementioned requirement, a water cooling type and air cooling thermoelement system has been proposed. Referring to FIG. 1, a thermoelectric element system of the related art improves cooling performance by changing a shape of a cooling tube. The thermoelectric element system according to the related art comprises cooling fins 310, thereby performing a cooling operation in an air-cooled manner as well as in a water-cooled manner. A thermoelectric device, into which a water cooling function and an air cooling function are incorporated, includes a heat absorbing part cooling tube 200 to which a thermoelectric element module 210 is attached. The heat absorbing part cooling tube 200 has a U shape so as to surround lower portions of heat transfer pipes 100 having two flat surfaces that face each other for heat conduction. A heat radiating part cooling tube 300 is formed to surround upper portions of the heat transfer pipes 100 and has the cooling fins 310 mounted therebetween. According to the related art, a cooling area may be increased, cooling efficiency is improved, and a cooling operation in an air-cooled manner is performed by using the cooled air from a radiator.
However, in the related art, since heat from a heat radiating part is transferred from a heat pipe to the cooling tube 300, the heat is generated at the cooling tube 300. Since the heat is transferred to the cooling tube 300 while repeatedly performing the heat exchange, a thermal loss occurs. A temperature of the heat radiating part decreases further, thus greatly degrading thermal efficiency. Further, the cooling tube 300 combined with the heat pipe of the heat radiating part has a complicated shape, and as a result, flow resistance occurs.
The thermoelectric device may be configured as a single module for a small-sized vehicle. However, a commercial vehicle requires a thermoelectric device having a large capacity, and thus, there is a great disadvantage in coupling the modules.
The above information disclosed in this Background section is only for enhancement of understanding the background of the disclosure, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.